In the future, it is likely that pollution monitoring agencies will require remote measuring techniques for many pollutants in order to properly monitor and control the environment. In the area of power plant smokestack effluents, the three major concerns are the particulates (fly ash), the NO and the SO.sub.2 emissions. Many techniques are presently being developed to remotely measure these effluents, such as laser radars, I. R. systems and correlation spectrometers. These devices are in various states of development; all are very expensive and difficult to operate and practically all suffer from a commmon problem, plume instability. This refers to the dynamic character of the plume which is a function of the exit velocity, ambient wind conditions and uniformity of the stack flow. An extreme case of these conditions is represented by the downwash situation which can cause serious deviations in the plume dimensions and hence in any effluent monitor's output signal. Of course, the change in signal cannot normally be attributed to the changes in plume geometry, but would more than likely be attributed to variations in the particular effluent's concentration.
It is therefore a primary object of this invention to provide a method and apparatus for measuring, at a remote location, smokestack effluents.
Another object of this invention is to provide a method and apparatus for measuring, at a remote location, the SO.sub.2 concentration at any selected point in the plume of a smokestack.
A further object of this invention is to provide a method and apparatus for measuring, at a remote location, the velocity of the emission of SO.sub.2 from a smokestack.
Other objects and advantages of this invention will further become apparent hereinafter and in the drawings.